<?php
/**
 * CDateTimeParser class file
 *
 * @author Wei Zhuo <weizhuo[at]gamil[dot]com>
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @author Tomasz Suchanek <tomasz[dot]suchanek[at]gmail[dot]com>
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2011 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CDateTimeParser converts a date/time string to a UNIX timestamp according to the specified pattern.
 *
 * The following pattern characters are recognized:
 * <pre>
 * Pattern |      Description
 * ----------------------------------------------------
 * d       | Day of month 1 to 31, no padding
 * dd      | Day of month 01 to 31, zero leading
 * M       | Month digit 1 to 12, no padding
 * MM      | Month digit 01 to 12, zero leading
 * yy      | 2 year digit, e.g., 96, 05
 * yyyy    | 4 year digit, e.g., 2005
 * h       | Hour in 0 to 23, no padding
 * hh      | Hour in 00 to 23, zero leading
 * H       | Hour in 0 to 23, no padding
 * HH      | Hour in 00 to 23, zero leading
 * m       | Minutes in 0 to 59, no padding
 * mm      | Minutes in 00 to 59, zero leading
 * s       | Seconds in 0 to 59, no padding
 * ss      | Seconds in 00 to 59, zero leading
 * a       | AM or PM, case-insensitive (since version 1.1.5)
 * ----------------------------------------------------
 * </pre>
 * All other characters must appear in the date string at the corresponding positions.
 *
 * For example, to parse a date string '21/10/2008', use the following:
 * <pre>
 * $timestamp=CDateTimeParser::parse('21/10/2008','dd/MM/yyyy');
 * </pre>
 *
 * To format a timestamp to a date string, please use {@link CDateFormatter}.
 *
 * @author Wei Zhuo <weizhuo[at]gmail[dot]com>
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CDateTimeParser.php 2928 2011-02-01 17:41:51Z alexander.makarow $
 * @package system.utils
 * @since 1.0
 */
class CDateTimeParser
{
    /**
     * Converts a date string to a timestamp.
     * @param string $value the date string to be parsed
     * @param string $pattern the pattern that the date string is following
     * @param array $defaults the default values for year, month, day, hour, minute and second.
     * The default values will be used in case when the pattern doesn't specify the
     * corresponding fields. For example, if the pattern is 'MM/dd/yyyy' and this
     * parameter is array('minute'=>0, 'second'=>0), then the actual minute and second
     * for the parsing result will take value 0, while the actual hour value will be
     * the current hour obtained by date('H'). This parameter has been available since version 1.1.5.
     * @return integer timestamp for the date string. False if parsing fails.
     */
    public static function parse($value,$pattern='MM/dd/yyyy',$defaults=array())
    {
        $tokens=self::tokenize($pattern);
        $i=0;
        $n=strlen($value);
        foreach($tokens as $token)
        {
            switch($token)
            {
                case 'yyyy':
                    {
                        if(($year=self::parseInteger($value,$i,4,4))===false)
                        return false;
                        $i+=4;
                        break;
                    }
                case 'yy':
                    {
                        if(($year=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($year);
                        break;
                    }
                case 'MM':
                    {
                        if(($month=self::parseInteger($value,$i,2,2))===false)
                        return false;
                        $i+=2;
                        break;
                    }
                case 'M':
                    {
                        if(($month=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($month);
                        break;
                    }
                case 'dd':
                    {
                        if(($day=self::parseInteger($value,$i,2,2))===false)
                        return false;
                        $i+=2;
                        break;
                    }
                case 'd':
                    {
                        if(($day=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($day);
                        break;
                    }
                case 'h':
                case 'H':
                    {
                        if(($hour=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($hour);
                        break;
                    }
                case 'hh':
                case 'HH':
                    {
                        if(($hour=self::parseInteger($value,$i,2,2))===false)
                        return false;
                        $i+=2;
                        break;
                    }
                case 'm':
                    {
                        if(($minute=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($minute);
                        break;
                    }
                case 'mm':
                    {
                        if(($minute=self::parseInteger($value,$i,2,2))===false)
                        return false;
                        $i+=2;
                        break;
                    }
                case 's':
                    {
                        if(($second=self::parseInteger($value,$i,1,2))===false)
                        return false;
                        $i+=strlen($second);
                        break;
                    }
                case 'ss':
                    {
                        if(($second=self::parseInteger($value,$i,2,2))===false)
                        return false;
                        $i+=2;
                        break;
                    }
                case 'a':
                    {
                        if(($ampm=self::parseAmPm($value,$i))===false)
                        return false;
                        if(isset($hour))
                        {
                            if($hour==12 && $ampm==='am')
                            $hour=0;
                            else if($hour<12 && $ampm==='pm')
                            $hour+=12;
                        }
                        $i+=2;
                        break;
                    }
                default:
                    {
                        $tn=strlen($token);
                        if($i>=$n || substr($value,$i,$tn)!==$token)
                        return false;
                        $i+=$tn;
                        break;
                    }
            }
        }
        if($i<$n)
        return false;

        if(!isset($year))
        $year=isset($defaults['year']) ? $defaults['year'] : date('Y');
        if(!isset($month))
        $month=isset($defaults['month']) ? $defaults['month'] : date('n');
        if(!isset($day))
        $day=isset($defaults['day']) ? $defaults['day'] : date('j');

        if(strlen($year)===2)
        {
            if($year>=70)
            $year+=1900;
            else
            $year+=2000;
        }
        $year=(int)$year;
        $month=(int)$month;
        $day=(int)$day;

        if(
        !isset($hour) && !isset($minute) && !isset($second)
        && !isset($defaults['hour']) && !isset($defaults['minute']) && !isset($defaults['second'])
        )
        $hour=$minute=$second=0;
        else
        {
            if(!isset($hour))
            $hour=isset($defaults['hour']) ? $defaults['hour'] : date('H');
            if(!isset($minute))
            $minute=isset($defaults['minute']) ? $defaults['minute'] : date('i');
            if(!isset($second))
            $second=isset($defaults['second']) ? $defaults['second'] : date('s');
            $hour=(int)$hour;
            $minute=(int)$minute;
            $second=(int)$second;
        }

        if(CTimestamp::isValidDate($year,$month,$day) && CTimestamp::isValidTime($hour,$minute,$second))
        return CTimestamp::getTimestamp($hour,$minute,$second,$month,$day,$year);
        else
        return false;
    }

    /*
     * @param string $pattern the pattern that the date string is following
     */
    private static function tokenize($pattern)
    {
        if(!($n=strlen($pattern)))
        return array();
        $tokens=array();
        for($c0=$pattern[0],$start=0,$i=1;$i<$n;++$i)
        {
            if(($c=$pattern[$i])!==$c0)
            {
                $tokens[]=substr($pattern,$start,$i-$start);
                $c0=$c;
                $start=$i;
            }
        }
        $tokens[]=substr($pattern,$start,$n-$start);
        return $tokens;
    }

    /*
     * @param string $value the date string to be parsed
     * @param integer $offset starting offset
     * @param integer $minLength minimum length
     * @param integer $maxLength maximum length
     */
    protected static function parseInteger($value,$offset,$minLength,$maxLength)
    {
        for($len=$maxLength;$len>=$minLength;--$len)
        {
            $v=substr($value,$offset,$len);
            if(ctype_digit($v) && strlen($v)>=$minLength)
            return $v;
        }
        return false;
    }

    /*
     * @param string $value the date string to be parsed
     * @param integer $offset starting offset
     */
    protected static function parseAmPm($value, $offset)
    {
        $v=strtolower(substr($value,$offset,2));
        return $v==='am' || $v==='pm' ? $v : false;
    }
}
